If you want to up load an image from your computer:
Click on "advanced"
Look for the paper clip and click on it. A window will pop up.
Click on "browse" and navigate to the pic you want.
Select the pick and click "upload"
If you want to link to a pic on a web page:
Open the web page in a new tab.
Right click on the pic and look at "properties"
Copy the url shown under the properties.
Return to tab with your thread.
Click on the small yellow envelope (you can find this under quick reply or advanced)
A window will pop up (you might have to temporarily allow popups)
Paste the url in the window.
HID